The present invention relates to working or reworking a diamond guide element by the use of a treating means which is moved relative to the guide element for grinding a profile.
The diamond guide element to which the invention is directed is used to guide a transducer, the guide element having a contact surface which, during the guiding process, bears on the surface of the record carrier while the latter is moved with respect to the guide element in the direction of a relative movement vector.
Starting from a vertex which lies on the contact surface of the guide element, there can be defined a directional vector which extends parallel to one of the wear-resistant directions of the diamond and substantially parallel to the plane of the direction of the contact force and of the relative movement vector. An acute angle .beta. .gtoreq. 0.degree. is formed between the longitudinal direction of the diamond contact surface, which has the ground-in profile, and the surface of the record carrier. A further acute angle .delta. .gtoreq. 0.degree. is formed between the above-mentioned directional vector, beginning at the vertex, and the longitudinal direction of the profiled contact surface, and an angle .gamma. .gtoreq. 0 is formed between the directional vector starting at the vertex, and the surface of the record carrier.
It has been found that during pressure scanning of very densely stored signals, and in view of corresponding small size of the diamond, the profile-ground contact surface wears rather rapidly.
It is known that wear of the contact surface can be counteracted by aligning the diamond guide element so that during scanning one of the most wear-resistant crystallographic directions of the diamond lies approximately in the direction of the relative movement of the record carrier with respect to the guide element or in the direction of the running edge. Wear-resistant directions in this connection are disclosed in German Pat. No. 2,060,317 issued Nov. 29, 1973, and in corresponding U.S. Pat. No. 3,781,020.
Although the longitudinal direction of the running edge of the relative movement direction of the guide element had been aligned with one of the most wear-resistant crystallographic directions, it was found that the quality of the scanned signals noticeably deteriorated after a short time during pressure scanning.
The reason for premature reduction in the scanning quality is not wear of the contact surface, but the deteriorating effectiveness of the sharp trailing edge which during pressure scanning is located between the contact surface and a limiting surface on the diamond. This edge may become round or, which is even worse, it may remain sharp but be subject to less pressure because of the more spherical shape of the contact surface, or may finally completely lose contact with the record carrier surface.
The guide element is provided with a ground-in profile which lies in a plane approximately perpendicular to the scanning direction when the guide element is used for pressure scanning the associated groove on the record carrier. In order for this precisely ground profile, and thus the scanning quality, to remain unchanged, the diamond is worked or reworked at its contact surface, as disclosed in German Offenlegungsschrift (Laid Open Application) No. 2,053,866 laid open on June 8, 1972.
This can be effected only during the time between two playback operations, i.e., in the intervals between scanning. It has here been found that working or reworking according to the known methods is very time consuming.
It is known to grind a diamond transversely to the most wear-resistant crystallographic direction. However, on a guide element with a ground profile such transverse grinding is impossible.